Rafael F. Lang, Wolfgang Seidel
Jun 17, 2009·astro-ph.IM·PDF The search for direct interactions of dark matter particles remains one of the most pressing challenges of contemporary experimental physics. A variety of different approaches is required to probe the available parameter space and to meet the technological challenges. Here, we review the experimental efforts towards the detection of direct dark matter interactions using scintillating crystals at cryogenic temperatures. We outline the ideas behind these detectors and describe the principles of their operation. Recent developments are summarized and various results from the search for rare processes are presented. In the search for direct dark matter interactions, the CRESST-II experiment delivers competitive limits, with a sensitivity below 5x10^(-7) pb on the coherent WIMP-nucleon cross section.
Rafael F. Lang
Most experiments that search for direct interactions of WIMP dark matter with a target can distinguish the dominant electronrecoil background from the nuclear recoil signal, based on some discrimination parameter. An acceptance region is defined inthe parameter space spanned by the recoil energy and this discrimination parameter. In the absence of a clear signal in thisregion, a limit is calculated on the dark matter scattering cross section. Here, an algorithm is presented that allows to define the acceptance region a priori such that the experiment has the best sensitivity. This is achieved through optimized acceptance regions for each WIMP model and WIMP mass that is to be probed. Using recent data from the CRESST-II experiment as anexample, it is shown that resulting limits can be substantially stronger than those from a conventional acceptance region. In an experiment with a segmented target, the algorithm developed here can yield different acceptance regions for the individual subdetectors. Hence, it is shown how to combine the data consistently within the usual Maximum Gap or Optimum Interval framework.
Jayden L. Newstead, Louis E. Strigari, Rafael F. Lang
Jul 18, 2018·astro-ph.SR·PDF We study the prospects for measuring the low-energy components of the solar neutrino flux in future direct dark matter detection experiments. We show that for a depletion of $^{136}$Xe by a factor of 100 relative to its natural abundance, and an extension to electron recoil energies of $\sim$ MeV, future xenon experiments with exposure $\sim 200$ ton-yr can detect the CNO component of the solar neutrino flux at $\sim 3 σ$ significance. A CNO detection will provide important insight into metallicity of the solar interior. Precise measurement of low-energy solar neutrinos, including as $pp$, $^7$Be, and $pep$ components, will further improve constraints on the "neutrino luminosity" of the Sun, thereby providing constraints on alternative sources of energy production. We find that a measurement of $L_ν/L_{\odot}$ of order one percent is possible with the above exposure, improving on current bounds from a global analysis of solar neutrino data by a factor of about seven.
Jayden L. Newstead, Rafael F. Lang, Louis E. Strigari
Feb 20, 2020·astro-ph.CO·PDF We study the sensitivity of future xenon- and argon-based dark matter and neutrino detection experiments to low-energy atmospheric neutrinos. Not accounting for experimental backgrounds, the primary obstacle for identifying nuclear recoils induced by atmospheric neutrinos is the tail of the electron recoil distribution due to $pp$ solar neutrinos. We use the NEST code to model the solar and atmospheric neutrino signals in a xenon detector and find that an exposure of 700 tonne-years will produce a $5σ$ detection of atmospheric neutrinos. We explore the effect of different detector properties and find that a sufficiently long electron lifetime is essential to the success of such a measurement.
Rafael F. Lang, Andrew Brown, Ethan Brown, Mayra Cervantes, Sean Macmullin, Darryl Masson, Jochen Schreiner, Hardy Simgen
We characterize two 40 kBq sources of electrodeposited Th-228 for use in low-background experiments. The sources efficiently emanate Rn-220, a noble gas that can diffuse in a detector volume. Rn-220 and its daughter isotopes produce alpha, beta, and gamma-radiation, which may used to calibrate a variety of detector responses and features, before decaying completely in only a few days. We perform various tests to place limits on the release of other long-lived isotopes. In particular, we find an emanation of <0.008 atoms/min/kBq (90% CL) for Th-228 and 1.53 atoms/min/kBq for Ra-224. The sources lend themselves in particular to the calibration of detectors employing liquid noble elements such as argon and xenon. With the source mounted in a noble gas system, we demonstrate that filters are highly efficient in reducing the activity of these longer-lived isotopes further. We thus confirm the suitability of these sources even for use in next-generation experiments, such as XENON1T/XENONnT, LZ, and nEXO.
Daniel Carney, Nirmal Raj, Yang Bai, Joshua Berger, Carlos Blanco, Joseph Bramante, Christopher Cappiello, Maíra Dutra, Reza Ebadi, Kristi Engel, Edward Kolb, J. Patrick Harding, Jason Kumar, Gordan Krnjaic, Rafael F. Lang, Rebecca K. Leane, Benjamin V. Lehmann, Shengchao Li, Andrew J. Long, Gopolang Mohlabeng, Ibles Olcina, Elisa Pueschel, Nicholas L. Rodd, Carsten Rott, Dipan Sengupta, Bibhushan Shakya, Ronald L. Walsworth, Shawn Westerdale
We outline the unique opportunities and challenges in the search for "ultraheavy" dark matter candidates with masses between roughly $10~{\rm TeV}$ and the Planck scale $m_{\rm pl} \approx 10^{16}~{\rm TeV}$. This mass range presents a wide and relatively unexplored dark matter parameter space, with a rich space of possible models and cosmic histories. We emphasize that both current detectors and new, targeted search techniques, via both direct and indirect detection, are poised to contribute to searches for ultraheavy particle dark matter in the coming decade. We highlight the need for new developments in this space, including new analyses of current and imminent direct and indirect experiments targeting ultraheavy dark matter and development of new, ultra-sensitive detector technologies like next-generation liquid noble detectors, neutrino experiments, and specialized quantum sensing techniques.
The Windchime Collaboration, Alaina Attanasio, Sunil A. Bhave, Carlos Blanco, Daniel Carney, Marcel Demarteau, Bahaa Elshimy, Michael Febbraro, Matthew A. Feldman, Sohitri Ghosh, Abby Hickin, Seongjin Hong, Rafael F. Lang, Benjamin Lawrie, Shengchao Li, Zhen Liu, Juan P. A. Maldonado, Claire Marvinney, Hein Zay Yar Oo, Yun-Yi Pai, Raphael Pooser, Juehang Qin, Tobias J. Sparmann, Jacob M. Taylor, Hao Tian, Christopher Tunnell
The absence of clear signals from particle dark matter in direct detection experiments motivates new approaches in disparate regions of viable parameter space. In this Snowmass white paper, we outline the Windchime project, a program to build a large array of quantum-enhanced mechanical sensors. The ultimate aim is to build a detector capable of searching for Planck mass-scale dark matter purely through its gravitational coupling to ordinary matter. In the shorter term, we aim to search for a number of other physics targets, especially some ultralight dark matter candidates. Here, we discuss the basic design, open R&D challenges and opportunities, current experimental efforts, and both short- and long-term physics targets of the Windchime project.
Bhaskar Dutta, Rafael F. Lang, Shu Liao, Samiran Sinha, Louis Strigari, Adrian Thompson
Neutrino non-standard interactions (NSI) with the first generation of standard model fermions can span a parameter space of large dimension and exhibit degeneracies that cannot be broken by a single class of experiment. Oscillation experiments, together with neutrino scattering experiments, can merge their observations into a highly informational dataset to combat this problem. We consider combining neutrino-electron and neutrino-nucleus scattering data from the Borexino and COHERENT experiments, including a projection for the upcoming coherent neutrino scattering measurement at the CENNS-10 liquid argon detector. We extend the reach of these data sets over the NSI parameter space with projections for neutrino scattering at a future multi-ton scale dark matter detector and future oscillation measurements from atmospheric neutrinos at the Deep Underground Neutrino Experiment (DUNE). In order to perform this global analysis, we adopt a novel approach using the copula method, utilized to combine posterior information from different experiments with a large, generalized set of NSI parameters. We find that the contributions from DUNE and a dark matter detector to the Borexino and COHERENT fits can improve constraints on the electron and quark NSI parameters by up to a factor of 2 to 3, even when relatively many NSI parameters are left free to vary in the analysis.
Yi Zhuang, Louis E. Strigari, Rafael F. Lang
The cosmic ray flux at the lowest energies, $\lesssim 10$ GeV, is modulated by the solar cycle, inducing a time variation that is expected to carry over into the atmospheric neutrino flux at these energies. Here we estimate this time variation of the atmospheric neutrino flux at five prospective underground locations for multi-tonne scale dark matter detectors (CJPL, Kamioka, LNGS, SNOlab and SURF). We find that between solar minimum and solar maximum, the normalization of the flux changes by $\sim 30\%$ at a high-latitude location such as SURF, while it changes by a smaller amount, $\lesssim 10\%$, at LNGS. A dark matter detector that runs for a period extending through solar cycles will be most effective at identifying this time variation. This opens the possibility to distinguish such neutrino-induced nuclear recoils from dark matter-induced nuclear recoils, thus allowing for the possibility of using timing information to break through the "neutrino floor."
Abigail Kopec, Amanda L. Baxter, Michael Clark, Rafael F. Lang, Shengchao Li, Juehang Qin, Riya Singh
We characterize single- and few-electron backgrounds that are observed in dual-phase liquid xenon time projection chambers at timescales greatly exceeding a maximum drift time after an interaction. These instrumental backgrounds limit a detector's sensitivity to dark matter and cosmogenic neutrinos. Using the ~150g liquid xenon detector at Purdue University, we investigate how these backgrounds, produced after 122keV $^{57}$Co Compton interactions, behave under different detector conditions. We find that the rates of single- and few-electron signals follow power-laws with time after the interaction. We observe linearly increasing rates with increased extraction field, and increased rates in the single-electron background with increased drift field. Normalizing the rates to the primary interaction's measured ionization signal, the rates increase linearly with the depth of the interaction. We test the hypothesis that infrared photons (1550nm) would stimulate and accelerate electron emission via photodetachment from impurities, but find that even 1 Watt of infrared light fails to reduce these backgrounds. We thus provide a characterization that can inform background models for low-energy rare event searches.
Michael Clark, Amanda Depoian, Bahaa Elshimy, Abigail Kopec, Rafael F. Lang, Shengchao Li, Juehang Qin
Multiply-interacting massive particles (MIMPs) are heavy (>10^10 GeV/c^2) dark matter particles that interact strongly with regular matter, but may have evaded detection due to the low number density required to make up the local dark matter halo. These particles could leave track-like signatures in current experiments, similar to lightly-ionizing particles. We show that previously calculated limits from the MAJORANA Demonstrator on the flux of lightly-ionizing particles can be used to exclude MIMP dark matter parameter space up to a mass of 10^15 GeV/c^2. We also calculate limits from the standard XENON1T analysis in this high-mass regime, properly taking into account flux limitations and multi-scatter effects. Finally, we show that a dedicated MIMP analysis using the XENON1T dark matter search could probe unexplored parameter space up to masses of 10^18 GeV/c^2.
Carlos Blanco, Bahaa Elshimy, Rafael F. Lang, Robert Orlando
In recent years, the sensitivity of opto-mechanical force sensors has improved leading to increased interest in using these devices as particle detectors. In this study we consider scenarios where dark matter with mass close to the Planck scale may be probed by a large array of opto-mechanical accelerometers. We motivate a macroscopic mechanical search for ultra-heavy dark matter, exemplified by the efforts of the Windchime collaboration, by providing a survey of the model space that would be visible to such a search. We consider two classes of models, one that invokes a new long-range unscreened force and another that is only gravitationally interacting. We identify significant regions of well-motivated, potentially visible parameter space for versatile models such as Q-balls, composite dark matter, relics of gravitational singularities, and gravitationally produced ultra-heavy particles.
Juehang Qin, Rafael F. Lang
We discuss the use of Gaussian random fields to estimate the look-elsewhere effect correction. We show that Gaussian random fields can be used to model the null-hypothesis significance maps from a large set of statistical problems commonly encountered in physics, such as template matching and likelihood ratio tests. Some specific examples are searches for dark matter using pixel arrays, searches for astronomical transients, and searches for fast-radio bursts. Gaussian random fields can be sampled efficiently in the frequency domain, and the excursion probability can be fitted with these samples to extend any estimation of the look-elsewhere effect to lower $p$-values. We demonstrate this using two example template matching problems. Finally, we apply this to estimate the trial factor of a $4^3$ accelerometer array for the detection of dark matter tracks in the Windchime project. When a global significance of $3σ$ is required, the estimated trial factor for such an accelerometer array is $10^{14}$ for a one-second search, and $10^{22}$ for a one-year search.
Florian Jörg, Shengchao Li, Jochen Schreiner, Hardy Simgen, Rafael F. Lang
Low-background liquid xenon detectors are utilized in the investigation of rare events, including dark matter and neutrinoless double beta decay. For their calibration, gaseous $^{220}$Rn can be used. After being introduced into the xenon, its progeny isotope $^{212}$Pb induces homogeneously distributed, low-energy ($<30$ keV) electronic recoil interactions. We report on the characterization of such a source for use in the XENONnT experiment. It consists of four commercially available $^{228}$Th sources with an activity of 55 kBq. These sources provide a high $^{220}$Rn emanation rate of about 8 kBq. We find no indication for the release of the long-lived $^{228}$Th above 1.7 mBq. Though an unexpected $^{222}$Rn emanation rate of about 3.6 mBq is observed, this source is still in line with the requirements for the XENONnT experiment.
Amanda L. Baxter, Rafael F. Lang, Craig Zywicki, Stephanie M. Gardner, Abigail Kopec, Andreas Jung
Course-based undergraduate research experiences (CUREs) increase students' access to research. This lesson plan describes an interdisciplinary CURE developed to be able to involve over 60 students per semester in original research using data from large particle physics experiments and telescopes, although the methods described can easily be adopted by other areas of data science. Students are divided into research teams of four, which greatly leverages the instruction time needed for mentoring, while increasing research productivity by creating accountability amongst the students. This CURE provides a strong framework, which minimizes barriers that students may perceive. This helps increase the number of students that benefit from a research opportunity while providing guidance and certainty. Through this CURE, students can engage in original research with the potential for publication-quality results, develop communication skills in various modes, and gain confidence in their performance as a scientist.
Spencer Chang, Rafael F. Lang, Neal Weiner
The inelastic dark matter scenario was proposed to reconcile the DAMA annual modulation with null results from other experiments. In this scenario, WIMPs scatter into an excited state, split from the ground state by an energy delta comparable to the available kinetic energy of a Galactic WIMP. We note that for large splittings delta, the dominant scattering at DAMA can occur off of thallium nuclei, with A~205, which are present as a dopant at the 10^-3 level in NaI(Tl) crystals. For a WIMP mass m~100GeV and delta~200keV, we find a region in delta-m-parameter space which is consistent with all experiments. These parameters in particular can be probed in experiments with thallium in their targets, such as KIMS, but are inaccessible to lighter target experiments. Depending on the tail of the WIMP velocity distribution, a highly modulated signal may or may not appear at CRESST-II.
Joseph Bramante, Benjamin Broerman, Jason Kumar, Rafael F. Lang, Maxim Pospelov, Nirmal Raj
We show that dark matter with a per-nucleon scattering cross section $\gtrsim 10^{-28}~{\rm cm^2}$ could be discovered by liquid scintillator neutrino detectors like BOREXINO, SNO+, and JUNO. Due to the large dark matter fluxes admitted, these detectors could find dark matter with masses up to $10^{21}$ GeV, surpassing the mass sensitivity of current direct detection experiments (such as XENON1T and PICO) by over two orders of magnitude. We derive the spin-independent and spin-dependent cross section sensitivity of these detectors using existing selection triggers, and propose an improved trigger program that enhances this sensitivity by two orders of magnitude. We interpret these sensitivities in terms of three dark matter scenarios: (1) effective contact operators for scattering, (2) QCD-charged dark matter, and (3) a recently proposed model of Planck-mass baryon-charged dark matter. We calculate the flux attenuation of dark matter at these detectors due to the earth overburden, taking into account the earth's density profile and elemental composition, and nuclear spins.
Yonatan Kahn, Maria Elena Monzani, Kimberly J. Palladino, Tyler Anderson, Deborah Bard, Daniel Baxter, Micah Buuck, Concetta Cartaro, Juan I. Collar, Miriam Diamond, Alden Fan, Simon Knapen, Scott Kravitz, Rafael F. Lang, Benjamin Nachman, Ibles Olcina Samblas, Igor Ostrovskiy, Aditya Parikh, Quentin Riffard, Amy Roberts, Kelly Stifter, Matthew Szydagis, Christopher Tunnell, Belina von Krosigk, Dennis Wright, Tien-Tien Yu, Dan Akerib, Ray Bunker, Thomas Y. Chen, Graciela B. Gelmini, Doojin Kim, Jong-Chul Park, Tarek Saab, Rajeev Singh, Shufang Su, Yu-Dai Tsai, Shawn Westerdale
This paper summarizes the modeling, statistics, simulation, and computing needs of direct dark matter detection experiments in the next decade.
Joseph Bramante, Benjamin Broerman, Rafael F. Lang, Nirmal Raj
We show that underground experiments like LUX/LZ, PandaX-II, XENON, and PICO could discover dark matter up to the Planck mass and beyond, with new searches for dark matter that scatters multiple times in these detectors. This opens up significant discovery potential via re-analysis of existing and future data. We also identify a new effect which substantially enhances experimental sensitivity to large dark matter scattering cross-sections: while passing through atmospheric or solid overburden, there is a maximum number of scatters that dark matter undergoes, determined by the total number of scattering sites it passes, such as nuclei and electrons. This extends the reach of some published limits and future analyses to arbitrarily large dark matter scattering cross-sections.
Jodi Cooley, Tongyan Lin, W. Hugh Lippincott, Tracy R. Slatyer, Tien-Tien Yu, Daniel S. Akerib, Tsuguo Aramaki, Daniel Baxter, Torsten Bringmann, Ray Bunker, Daniel Carney, Susana Cebrián, Thomas Y. Chen, Priscilla Cushman, C. E. Dahl, Rouven Essig, Alden Fan, Richard Gaitskell, Cristano Galbiati, Graciela B. Gelmini, Graham K. Giovanetti, Guillaume Giroux, Luca Grandi, J. Patrick Harding, Scott Haselschwardt, Lauren Hsu, Shunsaku Horiuchi, Yonatan Kahn, Doojin Kim, Geon-Bo Kim, Scott Kravitz, V. A. Kudryavtsev, Noah Kurinsky, Rafael F. Lang, Rebecca K. Leane, Benjamin V. Lehmann, Cecilia Levy, Shengchao Li, Ben Loer, Aaron Manalaysay, C. J Martoff, Gopolang Mohlabeng, M. E. Monzani, Alexander St J. Murphy, Russell Neilson, Harry N. Nelson, Ciaran A. J. O'Hare, K. J. Palladino, Aditya Parikh, Jong-Chul Park, Kerstin Perez, Stefano Profumo, Nirmal Raj, Brandon M. Roach, Tarek Saab, Maria Luísa Sarsa, Richard Schnee, Sally Shaw, Seodong Shin, Kuver Sinha, Kelly Stifter, Aritoki Suzuki, M. Szydagis, Tim M. P. Tait, Volodymyr Takhistov, Yu-Dai Tsai, S. E. Vahsen, Edoardo Vitagliano, Philip von Doetinchem, Gensheng Wang, Shawn Westerdale, David A. Williams, Xin Xiang, Liang Yang
This report summarizes the findings of the CF1 Topical Subgroup to Snowmass 2021, which was focused on particle dark matter. One of the most important scientific goals of the next decade is to reveal the nature of dark matter (DM). To accomplish this goal, we must delve deep, to cover high priority targets including weakly-interacting massive particles (WIMPs), and search wide, to explore as much motivated DM parameter space as possible. A diverse, continuous portfolio of experiments at large, medium, and small scales that includes both direct and indirect detection techniques maximizes the probability of discovering particle DM. Detailed calibrations and modeling of signal and background processes are required to make a convincing discovery. In the event that a candidate particle is found through different means, for example at a particle collider, the program described in this report is also essential to show that it is consistent with the actual cosmological DM. The US has a leading role in both direct and indirect detection dark matter experiments -- to maintain this leading role, it is imperative to continue funding major experiments and support a robust R\&D program.